Air duct cuff and method of manufacture

ABSTRACT

A method for manufacturing an air duct includes providing a tubular body having at least one open end which is inserted into an internal cuff mold to form an internal cuff that is secured to and axially extends from the tubular body. The tubular body and the internal cuff are removed from the internal cuff mold and then inserted into an external cuff mold to form an external cuff that is secured to and radially extends from at least the internal cuff. The tubular body with the internal cuff and the external cuff is then removed from the external cuff mold.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional application of U.S. patent applicationSer. No. 14/173,884 filed on Feb. 6, 2014, and which is incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates in general to an automotive clean air ductused to interconnect an automobile engine throttle body to an airfilter. More particularly, the present invention relates to a clean airduct with a cuff that is positioned on a receiving port, wherein thecuff has rigid and soft components. Specifically, the cuff is formedfrom a relatively rigid duct, which has an overmolded, relatively softinner cuff extending from the duct, and wherein the rigid duct and softinner cuff are both overmolded with a relatively rigid outer cuff.Related methods of manufacture are also disclosed.

BACKGROUND ART

Air ducts of various lengths and sizes are used to transfer clean,filtered air from an air filter through an engine air intake system. Itis also well known to use air ducts to transfer cooled or heated airfrom within the engine compartment to the passenger compartment of anautomobile. Air ducts are widely used in other applications wherever airor any other gas-like substance is transferred between components.

Air ducts have been formed by using a rubber molding process. Althoughthe rubber molded air ducts are effective, they are considered too heavyfor use in vehicles requiring lighter weight to improve fuel efficiency.Additionally, rubber molded air ducts are bulky and difficult to mold inthe serpentine configurations desired for automobiles which have limitedspace in the engine compartment.

An alternative to using a one-piece rubber molded air duct is atwo-piece construction which utilizes a thermoplastic blow moldedtubular body with an injection molded rubber cuff, sometimes called aseal, affixed to an end thereof. Although lighter and more compact thana rubber air duct, the two-piece construction has its own inherentproblems. The tubular body must be mechanically secured or adhesivelybonded to the seal to effect a connection therebetween that canwithstand the vibration and heat within an engine compartment.Furthermore, the connection between the tubular body and the molded sealtends to break after the air duct has been repeatedly detached andre-attached to the air filter or other receiving port. And theconnection is further stressed by the pressurized air flowing throughthe duct. A complete break in the connection between the tubular bodyand the seal renders the air duct unusable. Even a slight break betweenthe two parts may allow unwanted impediments to enter the air intakesystem of the engine. Moreover, the additional manufacturing steps ofindependently molding the rubber seal and securing the seal to thetubular body adds additional cost to the air duct.

Automotive air ducts are typically made of either hard or flexiblepolymers depending upon the particular end application. Seals or cuffsare typically made of a very soft elastomeric polymer material. Thecuffs are attached to a connection port in many ways including, but notlimited to, thermoplastic welding, worm-gear clamping, or overmolding.Overmolding is the most robust process for forming the cuff because itcreates a uniform melt bond to the hard polymer duct. However, suchconfigurations are problematic in that when the cuff formed between thehard polymer duct and the softer cuff is under a shear-type load, due toengine motion, or high internal air pressures, the cuff and related sealhas a tendency to tear because of their soft nature. One solution tothis tearing problem is to utilize a very expensive, reinforcedthermoset rubber hose.

However, the reinforced rubber hoses have a tendency to leak at flexpoints, thus ultimately leading to a failure of the duct and cuff.Therefore, there is a need in the art for an air duct configuration thatresists tearing, provides a permanent leak-free cuff, which does notflex and which can be made at a lower cost than a reinforced rubberhose.

DISCLOSURE OF THE INVENTION

It is therefore an object of the present invention to provide an airduct cuff and method of manufacture.

It is another object of the present invention to provide an air duct fortransferring air or the like from one component to another, the ductcomprising a tubular body, an internal cuff secured to and extendingaxially from the tubular body, and an external cuff secured to andextending radially from at least the internal cuff.

It is yet another object of the present invention to provide a methodfor manufacturing an air duct, comprising providing a tubular bodyhaving at least one open end, inserting the tubular body and the atleast one open end into an internal cuff mold and forming an internalcuff that is secured to and axially extends from the tubular body,removing the tubular body and the internal cuff from the internal cuffmold, inserting the tubular body and the internal cuff into an externalcuff mold and forming an external cuff that is secured to and radiallyextending from at least the internal cuff, and removing the tubular bodywith the internal cuff and the external cuff from the external cuffmold.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention willbecome better understood with regard to the following description,appended claims, and accompanying drawings. Further, in the accompanyingdrawings and description that follow, like parts are indicatedthroughout the drawings and written description with the same referencenumerals, respectively. The figures may or may not be drawn to scale andproportions of certain parts may be exaggerated for convenience ofillustration.

FIG. 1 is a perspective view of an air duct cuff assembly made inaccordance with the concepts of the present invention;

FIG. 2A is a perspective view of a tubular body utilized in the air ductcuff assembly according to the concepts of the present invention;

FIG. 2B is a cross-sectional view taken along lines 2B-2B of FIG. 2Ashowing the tubular body;

FIG. 3A is a perspective view of an internal cuff utilized with the airduct cuff assembly according to the concepts of the present invention;

FIG. 3B is a cross-sectional view of the internal cuff taken along lines3B-3B of FIG. 3A according to the concepts of the present invention;

FIG. 4A is a perspective view of a sub-assembly showing the internalcuff connected to the tubular body according to the concepts of thepresent invention;

FIG. 4B is a cross-sectional view of the sub-assembly taken along lines4B-4B of FIG. 4A and a schematic representation of an injection mold forforming the sub-assembly according to the concepts of the presentinvention;

FIG. 5A is a perspective view of an external cuff utilized with the airduct cuff assembly in accordance with the concepts of the presentinvention;

FIG. 5B is a cross-sectional view of the external cuff taken along lines5B-5B of FIG. 5A in accordance with the concepts of the presentinvention;

FIG. 6 is a cross-sectional view of the completed air duct cuff assemblyas formed in another schematic representation of an injection mold inaccordance with the concepts of the present invention;

FIG. 7 is an exploded view showing the air duct cuff assembly and a portto which the cuff assembly is connected or mounted; and

FIG. 8 is an enlarged cross-sectional view of a portion of the air ductcuff assembly mounted to the port in accordance with the concepts of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to the drawings, and in particular to FIG. 1, it can beseen that an air duct cuff assembly is designated generally by thenumeral 10. The assembly 10 is receivable and/or mounted to a port suchas an air filter, an engine compartment, a throttle body or othersimilar structure. Although the air duct disclosed herein is used inautomobile engine compartments, skilled artisans will appreciate thatthe duct and associated cuff assembly disclosed herein may be utilizedin any environment where air or a gas needs to be transferred from onecompartment to another and in such a way so as to seal the duct fromexternal contaminants.

Generally, the air duct cuff assembly 10 comprises a tubular body 12.The tubular body may be straight, contoured, angled or provided withpleats so as to allow for flexibility of the body and in any desiredlength. It will further be appreciated that the body 12 does not need tobe tubular, but can be any appropriately configured shape to facilitatemanufacturing, although it is believed that a tubular configuration,which can be constructed by blow molding or injection molding, will bethe most cost-effective construction. Connected or mounted to at leastone end of the tubular body 12 is an internal cuff 14. Connected to andmounted around the internal cuff 14 and the tubular body 12 is anexternal cuff 18. Skilled artisans will appreciate that the tubular bodymay be provided where both ends provide both the internal cuff 14 andexternal cuff 18. As will become apparent as the detailed descriptionproceeds, the air duct cuff assembly 10 provides certain advantagesbased upon the materials and structural configuration of the tubularbody 12, the internal cuff 14, and the external cuff 18. Additionally,the air duct cuff assembly 10 is formed utilizing two separateovermolding processes. In the disclosed embodiment, the overmoldingprocess is an injection-type molding process, but it will be appreciatedthat other molding processes could be employed. Moreover, otherconstruction processes could be employed wherein the parts areseparately formed and then secured to one another by other means. In anyevent, overmolding is chosen because it is believed to be the mostrobust way to attach a cuff to an end of an air duct. And also the mosteconomical.

In forming the air duct cuff assembly, the first operation isaccomplished by injecting and overmolding a soft seal cuff material ontoa relatively harder tubular body material. Utilization of a softerelastomer material creates a melt bond providing a 100% leak-free seal.After further processing, a second overmolding operation is employedwherein both the internal cuff and the tubular body are overmoldedutilizing a relatively harder polymeric material so as to form theexternal cuff 18 which is also bonded and connected to the tubular body.The external cuff overmold provides the strength needed to prevent theinternal cuff from tearing under a shear load or bursting under highinternal air pressures. The completed assembly may be secured to a portor duct by securing a worm gear clamp around the completed cuff toprovide a maximum sealing force to prevent failure. In other words, amechanical clamp may be secured around the harder external cuffmaterial. The external cuff and internal cuff are constructed in such away that application of a clamping force to the external cuff evenlydistributes the clamping force to the internal cuff, which is mounted toand seals around an appropriately sized port.

Referring now to FIGS. 2A and 2B, it can be seen that the tubular body12 is provided, wherein only one end is shown. In any event, the tubularbody 12 includes an exterior surface 22 opposite an interior surface 24.An end 26 connects the exterior and interior surfaces to one another.The tubular body 12 forms a body interior 30, which provides the openingor void to allow for transfer of air or other gaseous materials betweenends of the tubular body. An end flange 32 may be disposed near the end26. Although the end flange 32 is shown immediately adjacent to the end26, skilled artisans will appreciate that the end flange 32 may beslightly displaced from the end 26.

The end flange 32 includes an angular ramp 34 that extends from theexterior surface 22 or the end 26. The angle of the angular ramp 34 mayrange anywhere from 5 degrees to 85 degrees, although it is believedthat angles of 30 degrees to 55 degrees may be utilized in mostembodiments. The angular ramp 34 terminates at an end flange exterior36, which provides a relatively flat portion that is substantiallyparallel with the exterior surface 22. However, the end flange exterior36 may be provided in a non-parallel configuration. An end flange step38 extends from the exterior 36 to the exterior surface 22. The step 38is likely substantially perpendicular with the exterior surface 22, butit may also be provided at some other angle.

Positioned away from the end flange 32 and the end 26 may be a cuffflange 42. The cuff flange 42 and the end flange 32 may be separated bya bridge surface 40, which, in most embodiments, has the same diameteras the exterior surface 22. However, the bridge surface 40 diameter mayvary somewhat from the diameter of the exterior surface 22. In anyevent, the cuff flange 42 is configured in much the same manner as theend flange 32. The cuff flange 42 includes an angular ramp 44 extendingfrom the bridge surface 40. The angular ramp 44 may have the sameattributes as the angular ramp 34. Connected to and extending from theangular ramp 44 is a cuff flange exterior 46, which is substantiallyparallel, in most embodiments, to the exterior surface 22. However, anon-parallel arrangement of the cuff flange exterior 46 may be provided.Extending substantially perpendicularly from the cuff flange exterior 46is a cuff flange step 48, which terminates at its opposite end with theexterior surface 22.

The tubular body 12, in most embodiments, is manufactured utilizing ablow-molding process. In some embodiments, the body may be configured byextrusion or injection molding. The tubular body may be made from apolymeric material such as polypropylene manufactured by Lyondell Basselunder port number Pro-Fax™ SV152 which has a hardness value of 78 ShoreD. Skilled artisans will appreciate that other polymeric materialshaving similar properties and values may also be utilized. Othersuitable materials that could be used for the tubular body 12 are: nylonmanufactured by BASF under the part number Ultrmid™ 827G which has ahardness value of 121 Shore R; nylon 6/6 manufactured by DuPont underpart number Zytel™ BM70G20HSLX which has a hardness value of 120 ShoreR; or thermoplastic elastomer manufactured by Teknor Apex under partnumber Sarlink™ 4190B which has a hardness value of 90 Shore A.Accordingly, in some embodiments the material used for the tubular body12 may have a hardness value ranging anywhere from about 70 Shore A toabout 130 Shore R, and in other embodiments from about 90 Shore A toabout 121 Shore R.

Referring now to FIGS. 3A, 3B, 4A and 4B, it can be seen that theinternal cuff 14 is molded, formed, assembled and/or otherwise securedto the tubular body 12. FIGS. 3A and 3B present the internal cuff byitself so as to allow for clear delineation of its structural features,while FIGS. 4A and 4B show the connection between the tubular body 12and the internal cuff 14.

Specifically referring to FIGS. 3A and 3B, it can be seen that theinternal cuff 14 includes an internal cuff body 50. The internal cuffbody is constructed of a polymeric material and, in particular, apolymeric material which, in most embodiments, is relatively softer thanthe polymeric material utilized for the tubular body. In mostembodiments, the internal cuff may be made from thermoplastic elastomerwhich is manufactured by RTP Company under part number RTP™ 6091-65which has a hardness value of 65 Shore A. Other polymeric materialshaving similar properties and values may be utilized. Other suitablematerials that could be used for the internal cuff are: thermoplasticelastomers manufactured by Exxon Mobile part number Satoprene™ 101-55,which has a hardness value of 55 Shore A, or Santoprene™ 101-64 whichhas a hardness value of 64 Shore A. Other suitable thermoplasticelastomers are manufactured by Teknor Apex under part numbers Sarlink4175B, which has a hardness value of 75 Shore A, or Sarlink 4180B whichhas a hardness value of 80 Shore A. The RTP Complany also manufacturesthermoplastic elastomers RTP™ 6091-65, which has a hardness value of 65Shore A, and RTP 6091-85, which has a hardness value of 85 Shore A. Aliquid silicone rubber material manufactured by Wacker Chemical underpart number LR 3070/60 which has a hardness value of 60 Shore A may alsobe utilized. Accordingly, in some embodiments, the material used for theinternal cuff may have a hardness value ranging anywhere from about 45Shore A to about 90 Shore A, and in other embodiments from about 55Shore A to about 80 Shore A.

In the embodiment shown, the internal cuff body is formed by aninjection-molding process over-molded to the tubular body 12. However,skilled artisans will appreciate that other manufacturing procedurescould be utilized to secure and connect the internal cuff to the tubularbody. These other procedures may include, but are not limited to,mechanical or adhesive attachments, spin-welding or other heatsecurement processes. However, it is believed that the injection-moldingprocess provides both cost and structural benefits over the otheraforementioned processes.

The internal cuff body 50 includes a body end 52, which has an endchamfer 56 internally directed. In most embodiments the chamfer 56 mayextend at about a 45-degree angle, although other angles may beemployed. Skilled artisans will appreciate that the chamfer is employedso as to allow or facilitate mounting of the completed assembly 10 ontoan appropriate port. In any event, the end chamfer 56 extends into aninternal cuff interior 58. Radially extending inwardly from the interior58 is at least one internal rib 60. As will become apparent, theinternal rib or ribs 60 provide for a gripping force on the port ontowhich the completed assembly is mounted. Two internal ribs 60 are shown,but it will be appreciated that any number of internal ribs may beprovided. The interior 58 may also provide for an internal extending lip64. As such, the lip 64 extends from the interior 58 so that the lip 64forms a larger inner diameter than the interior 58. The lip 64 may beprovided to mount over a corresponding outward protuberance at an end ofthe port that is received in the completed assembly 10.

The internal lip 64 provides for a lip ramp 66 extending from theinterior 58, which may be provided at any angle ranging from 5 degreesto 85 degrees, and in most embodiments will range between 35 degrees to55 degrees. Extending from the lip ramp 66 is an internal ring 68, whichmay be substantially parallel with the outer exterior surface of thecuff body 50. Angularly extending from the internal ring 68 is a lipincline 70. The lip incline 70 may extend from the internal ring 68 atan angle ranging from zero to about 80 degrees. The lip incline 70extends to an internal stop 72, which is substantially parallel with thecuff interior 58. As is evident from FIG. 3B, the diameter of theinternal stop 72 is somewhat less than the diameter of the internal cuffinterior 58.

Extending from the internal stop 72 is an end flange groove 74. As willbecome apparent as the description proceeds, the end flange groove 74fits around and is secured to the end flange 32 of the tubular body 12.The end flange groove 74 includes a groove wall 76, which issubstantially perpendicular to the internal stop 72. Angularly extendingfrom the groove wall 76 is a groove flange 78 wherein the groove flange78 may extend at any angle ranging between 5 degrees to 80 degrees withrespect to the groove wall 76. Extending from the groove flange 78 is agroove flat 80, which is substantially parallel with the internal cuff'sexterior surface. Extending substantially perpendicularly from thegroove flat 80 is a groove step 82.

Extending further from the groove step 82 is an internal cuff collar 86.This surface may be substantially parallel with the internal stop 72 andthe exterior of the cuff body 50. A collar end 88 extends substantiallyperpendicularly from the internal cuff collar 86 and is the end of theinternal cuff opposite the body end 52. Extending from the collar end 88is a collar exterior 90, which angularly transitions along a collar ramp92 to an internal cuff exterior 94. The internal cuff exterior 94 isthen connected to the body end 52.

Referring now to FIGS. 4A and 4B, it can be seen that a sub-assembly isdesignated generally by the numeral 100, wherein the sub-assemblyincludes the internal cuff 14 secured to the tubular body 12. Thesub-assembly 100 is formed by insertion of an internal cuff mold mandrel102 into the tubular body interior 30. The mold mandrel 102 extends toat least a portion of the tubular body beyond the cuff flange 42 thatradially extends from the exterior surface of the tubular body. Asskilled artisans will appreciate, the mold mandrel provides anunderlying structure that is capable of supporting at least asubstantial portion of the interior surfaces of the tubular body 12 andalso allows for formation of the internal surfaces of the internal cuff14. However, in some embodiments, the rigidity of the tubular body maybe sufficient such that the mandrel 102 is not needed to extend into thetubular body to enable the molding operation that forms the cuff. A cuffmold 104A and 104B—which may be formed in halves or other number ofparts—clamps around the mold mandrel 102 and the exterior surface 22 ofthe tubular body. Once a complete seal is formed between the mold 104,the mold mandrel 102 and the exterior surface of the tubular body, apolymeric material is injected into the mold 104A/B so as to form theinternal cuff and resulting sub-assembly. Once the molding operation iscomplete and the polymeric material is cooled and allowed tosufficiently set, the mold 104 is opened and the mold mandrel 102 iswithdrawn so as to provide the completed sub-assembly 100.

Referring now to FIGS. 5A and B, it can be seen that the external cuff18 is designated generally by the numeral 118. As will become apparentas the description proceeds, the external cuff 18 is over molded on tothe sub-assembly 100. The external cuff 18 is manufactured of apolymeric material having a hardness that is relatively harder than thematerial used for the internal cuff. In most embodiments, the externalcuff is made from nylon 6 manufactured by BASF under part numberUltramid™ 8202 which has a hardness value of 100 Shore R. An alternativematerial is polypropylene manufactured by LyondellBassell under theirpart number Pro-Fax™ and SB891 which has a hardness value of 78 Shore D.Of course, other suitable materials may be utilized. Accordingly, insome embodiments, the material used for the external cuff may have ahardness value from about 60 Shore D to about 110 Shore R, and in otherembodiments from about 78 Shore D to about 100 Shore R. In someembodiments, the external cuff material may be harder than the tubularbody material. And in some embodiments the tubular body material may beharder than the external cuff material. Selection of the cuff materialsand the tubular body material and their corresponding hardness valuesare dependent upon the particular end use of the completed assembly 10.And combination of materials in the above-identified ranges may be used.

The external cuff 18 is shown by itself in FIGS. 5A and 5B and such anindividual component may be manufactured and then mechanically oradhesively secured and connected to the sub-assembly 100. However, it isbelieved that, as with the formation of the internal cuff on the tubularbody, the optimal method of manufacture is by injection molding as willbe described in relation to FIG. 6. In any event, the external cuff 18comprises an external cuff body 110. The external cuff body is formedwith an external lip end 112, which radially extends from a neck 114. Inmost embodiments, the external lip end 112 extends substantiallyperpendicularly from the neck. Angularly extending from the neck 114, atan end opposite the lip end 112, is a shoulder 116 wherein the shoulderextends from the neck at an angle ranging anywhere from 10 degrees to 85degrees, and in most embodiments will range from 35 degrees to 55degrees. Extending from the shoulder 116 is a wall 120, which issubstantially parallel with the neck 114. Extending inwardly radiallyfrom the wall 120 is a tapered end 122, which is opposite the externallip end 112. Skilled artisans will appreciate that the exterior surfaceof the external cuff body 110 includes the lip end 112, the neck 114,the shoulder 116, the wall 120, and the tapered end 122.

The internal surfaces of the external cuff body may be formed in themolding process so as to surround and connect to the external surfacesof the internal cuff and a portion of the exterior surface of thetubular body which encompasses at least the cuff flange 42.

Extending substantially perpendicularly from the tapered end 122 is anexternal cuff body internal surface 126. The surface 126 provides for acuff flange groove 130 that fits around and is secured to the cuffflange 42 of the tubular body 12. The cuff flange groove 130 includes agroove flat 132 which is substantially perpendicular to the internalsurface 126. Extending substantially perpendicularly from the grooveflat 132 is a groove flange 134, which provides a surface that issubstantially parallel with the internal surface 126. Angularlyextending from the groove flange 134 is a groove step 136 that matcheswith the groove flange 78 of the internal cuff. The groove step 136 hasa complementary angle of the groove flange 78 in relation to theinternal surface 126. Extending from the groove step 136 is the internalsurface 126 which extends to a collar rim 138, which also forms aroundthe exterior surface of the internal cuff 14. Extending substantiallyperpendicularly from the collar rim 138 is a collar groove 140, whichtransitions to a collar shoulder 144 which transitions to a throatsurface 146. The throat surface 146 terminates at the external lip end112. As such, the external cuff body provides internal surfaces that areformed by the internal surface 126, the cuff flange groove 130, thecollar rim 138, the collar groove 140, the collar shoulder 144, and thethroat 146. In the embodiment shown, all of these internal surfaces areformed in the molding process that forms the external cuff 18. Moreover,these internal surfaces are formed by the external surfaces of theinternal cuff and the exterior surface of the tubular body.

The external cuff 14 also provides exterior structural features that maybe utilized in the completed assembly. In particular, a plurality ofexternal tabs 150 may extend from the shoulder 116 and neck 114 atangular increments about the external cuff. These tabs 150 may beutilized to provide for reinforcement of the external cuff and may alsobe utilized to position and retain components of a clamping device,which is not shown.

The external cuff 14 also provides for at least one end notch 154. Theend notch 154 extends from the external lip end 112 toward the shoulder116. In the embodiment shown, the end notch 154 terminates at a notchapex 156 wherein notch sides 160A and 160B extend from the apex towardthe end lip. This angular notch allows for the external cuff material tobe somewhat radially deflected. In other words, when a band clamp orother clamping device is secured around the outer periphery of theexternal cuff, and in particular the neck 114, a radial compressiveforce is applied from the relatively rigid external cuff to therelatively soft internal cuff and correspondingly toward the port thatreceives the air duct cuff assembly 10. The number of notches selecteddepends upon the combination of materials selected for the external andinternal cuffs so as to insure that a sufficient clamping force can beexerted on the cuffs without adversely affecting any of the bondsbetween the cuffs and the tubular body. Moreover, it will be appreciatedthat the thickness of external cuff may vary in thickness depending onthe chosen hardness in view of the desire to allow the external cuff toflex slightly to permit installation of the completed assembly 100 on tothe mating duct or tube. It will further be appreciated that in additionto the configuration of the notches 154 and the thickness of theexternal cuff at the neck 114, the shoulder 116, the wall 120 and thetapered end 122, and the hardness properties of the material used, thatflexibility of the external cuff can be adjusted by the dimensional andphysical properties of the internal cuff and the positioning of theinternal surface 126 with respect to the end 26 of the tubular body 12.

Referring now to FIG. 6, it can be seen that the air duct cuff assembly10 is formed by a final assembly mold 170. A mold includes a mandrel 172that may at least support a portion of the internal cuff 14 and in someembodiments may also support some of the interior surfaces of thetubular body. At a minimum, the mandrel 172 provides for a sealingsurface for the mold halves 174A and 174B, which seal around the mandreland also the external surface of the tubular body 12. The mold halves174A and 174B are positioned so as to exert a sealing surface around theinternal cuff 141 and the tubular body 12. Once the mold is closed andsealed, a polymeric material is injected into the mold cavity whichforms the external cuff 18. After the polymeric material has cooled andset, the mold 174 A/B is opened, and the mandrel 172 withdrawn and anyother appropriate finishing steps are completed.

As best seen in FIG. 8, the external cuff conforms to the exteriorsurface of the tubular body about the cuff flange 42 and also around asubstantial portion of the internal cuff around the collar exterior 90.Due to the flexing of the neck 114 because of the notches 154, there isminimal bonding, if any, between the neck 114 and the underlyinginternal cuff exterior 94.

Once the assembly is completed as shown in FIGS. 7 and 8, the assembly10 is fitted upon a port 180 and an appropriate clamping device may besecured around the cuff assembly so as to secure it to the exteriorsurface of the port.

Based on the foregoing, the advantages of the present construction arereadily apparent. The air duct cuff assembly 10 provides for a secureconnection to a port, and more importantly a connection that canwithstand significant shear loads and maintain a desired seal even whenhigh internal air pressures are exerted within the tubular body 12. Thecuff assembly 10 resists tearing, provides a permanent leak-free seal,does not flex in an unwanted manner, and can be made at a significantlylower cost than other types of air duct assemblies. The construction isfurther advantageous by the utilization of different hardness of polymermaterials for the tubular body and, in particular, the internal cuff andthe external cuff. Utilization of a relatively soft polymeric materialfor the internal cuff allows for compressive forces to be applied so asto maintain a desired seal. Utilization of a relatively harder materialfor the external cuff allows for that material to withstand the clampingforces without initiating a tear, which would likely occur when theclamping forces are directly applied to the softer internal cuffpolymeric material. In other words, the external harder material is ableto withstand the applied forces exerted by a band clamp or the like, andthose forces are uniformly and evenly distributed about the relativelysofter internal cuff material so as to provide a desired seal around aport or other similar duct device that is inserted into the assembly 10.

Thus, it can be seen that the objects of the invention have beensatisfied by the structure and its method for use presented above. Whilein accordance with the Patent Statutes, only the best mode and preferredembodiment has been presented and described in detail, it is to beunderstood that the invention is not limited thereto or thereby.Accordingly, for an appreciation of the true scope and breadth of theinvention, reference should be made to the following claims.

What is claimed is:
 1. A method for manufacturing an air duct,comprising: providing a tubular body having at least one open end;obturating said at least one open end with an internal cuff mandrel;inserting said tubular body and said at least one open end into aninternal cuff mold; sealing said internal cuff mold around said internalcuff mandrel and said tubular body; injecting an internal cuff polymericmaterial into said internal cuff mold and forming an internal cuff thatis secured to and axially extends from said tubular body; removing saidtubular body and said internal cuff from said internal cuff mold;inserting said tubular body and said internal cuff into an external cuffmold and forming an external cuff that is secured to and radiallyextending from at least said internal cuff; and removing said tubularbody with said internal cuff and said external cuff from said externalcuff mold.
 2. The method according to claim 1, further comprising:obturating said tubular body and said internal cuff with an externalcuff mandrel; sealing said external cuff mold around said internal cuffand said tubular body; and injecting an external cuff polymeric materialinto said external cuff mold so as to form said external cuff secured tosaid internal cuff and said tubular body.
 3. The method according toclaim 2, wherein said external cuff polymeric material is relativelyharder than said internal cuff polymeric material.
 4. A method formanufacturing an air duct comprising: providing a tubular body having atleast one open end; inserting said tubular body and said at least oneopen end into an internal cuff mold and forming an internal cuff that issecured to and axially extends from said tubular body; removing saidtubular body and said internal cuff from said internal cuff mold;inserting said tubular body and said internal cuff into an external cuffmold; sealing said external cuff mold around said internal cuff and saidtubular body and forming an external cuff that is secured to andradially extending from at least said internal cuff; and removing saidtubular body with said internal cuff and said external cuff from saidexternal cuff mold.
 5. The method according to claim 4, furthercomprising: forming substantially axially extending notches in saidexternal cuff.
 6. A method for manufacturing an air duct comprising:providing a tubular body having at least one open end; inserting saidtubular body and said at least one open end into an internal cuff moldand forming an internal cuff that is secured to and axially extends fromsaid tubular body; removing said tubular body and said internal cufffrom said internal cuff mold; obturating said tubular body and saidinternal cuff with an external cuff mandrel; inserting said tubular bodyand said internal cuff into an external cuff mold; sealing said externalcuff mold around said internal cuff and said tubular body; injecting anexternal cuff polymeric material into said external cuff mold andforming an external cuff that is secured to and radially extending fromat least said internal cuff and said tubular body; and removing saidtubular body with said internal cuff and said external cuff from saidexternal cuff mold.